Field of the Invention
The present disclosure relates to an eyepiece lens, and an observation apparatus and an imaging apparatus including an eyepiece lens, and the eyepiece lens, and the observation apparatus and the imaging apparatus including the eyepiece lens, are well adaptable to observe an image displayed on an image display device in an electronic viewfinder used for an optical device or a camera, such as, a video camera, a still camera, or a broadcasting camera, for example.
Description of the Related Art
An electronic viewfinder used in an optical device such as a video camera or a broadcasting camera has conventionally used an eyepiece lens to enlarge and observe an image displayed on a liquid crystal screen provided in the camera.
Recently, with an increase in functions of an imaging apparatus, an electronic viewfinder having a wide visual field and capable of largely displaying an image has been demanded. As a method for achieving such demand, a method of increasing an image display surface such as a liquid crystal screen, or a method of increasing an observation magnification of an eyepiece lens, has been known.
However, a large image display surface increases the size of the viewfinder. To downsize the overall viewfinder, the observation magnification of the eyepiece lens is preferably increased. To increase the observation magnification of the eyepiece lens, the positive refractive power of the eyepiece lens needs to be high. At this time, if the eyepiece lens is constituted by only lenses with a positive refractive power (positive lenses), axial chromatic aberration and lateral chromatic aberration are greatly generated, and it becomes difficult to correct these aberrations. To obtain a high-definition observation image with an observation magnification of an eyepiece lens being increased, an eyepiece lens is desirably configured by using a lens having a negative refractive power (negative lens) in addition to a positive lens. With this configuration, an observation image in which axial chromatic aberration and lateral chromatic aberration are satisfactorily corrected can be obtained.
In addition, a finder which has a long eye relief and which can be used by a user with glasses has been demanded.
Japanese Patent Application Laid-Open No. 2001-272610 discusses an eyepiece lens which is constituted by a positive lens, a negative lens, a positive lens, a negative lens, and a positive lens sequentially from an image display surface side to an observation side (eye point side). This application aims to implement an eyepiece lens having a short focal length and long eye relief by using a plurality of positive lenses.
Japanese Patent No. 3306134 discusses an eyepiece lens which is constituted by a positive lens, a positive lens, a negative lens, a positive lens, and a positive lens sequentially from an image display surface side to an observation side (eye point side). This patent aims to increase an angle of view by using four positive lenses.
As described above, an eyepiece lens including five lenses as a whole has been known. The eyepiece lens includes at least one positive lens and one negative lens for implementing a long eye relief and wide angle of view.
In the eyepiece lens discussed in Japanese Patent Application Laid-Open No. 2001-272610, the positive lens (second positive lens) that is arranged second from the image display surface out of the three positive lenses has the highest refractive power, and it is difficult to satisfactorily correct coma and high-order aberration generated in the second lens.
In the eyepiece lens discussed in Japanese Patent No. 3306134, four of the five lenses are positive lenses, and it is difficult to satisfactorily correct axial chromatic aberration and lateral chromatic aberration.